Factors influencing the extraction and association of MAu(CN)(2) ion pairs in organic solvents are elucidated. For extraction of aurocyanide ion pairs with small cations (H+, Li+, Na+, K+), the most important factor is the solubility of water in the solvent. High extraction efficiencies are related to low association constants for these cations. For extraction of aurocyanide ion pairs with larger, less hydrated cations (Cs+, NEt4+), other solvent-specific parameters, such as dielectric constant and hydrogen-bonding ability, play a role.